1. Field of the Invention
The present invention relates to a crude oil production system and more specifically, to a mover stabilizing and stator cooling arrangement used in a 3-phase linear motor of a submersible oil pump to stabilize reciprocating movement of the mover and to dissipate heat from the stator during operation of the motor.
2. Description of the Related Art
The best way to dissipate heat during operation of a motor is the utilization of natural air convection. Electric fan may be used to provide forced air, enhancing heat dissipation.
U.S. Pat. No. 7,316,270 discloses an oil pumping unit using a submersible oil pump driven by a synchronizing three-phase linear motor. According to this design, the oil pumping unit comprises a motor 10 and a pump 20. The motor 10 comprises a casing 13, a stator 12, and a mover 11. The mover 11 comprises a center tube 14. The pump 20 comprises a barrel 23, a suction pipe 21, an upper chamber 25, a piston 26, and a lower chamber 27. The suction pipe 21 is connected to the mover 11 for synchronous reciprocation to suck in a fluid from the oil well.
According to this design, natural air or forced air cannot reach the inside of the linear motor 10 to dissipate heat from the linear motor 10. When the pump is pumping the fluid, the running fluid passing through the center tube 14 carries heat away from the mover 11. However, the air gap between the mover 11 and the stator 12 does not transfer heat easily, therefore heat tends to be accumulated at the stator 12. Further, the mover 11 of the linear motor 10 is relatively quite long, therefore off axial motion can easily happen during its reciprocating motion. An improvement is necessary to facilitate heat dissipation of the stator 12 and to stabilize the axial reciprocating motion of the mover 11.